The role of urine derived exosome metalloproteinases as biomarkers for prostate cancer detection may be confounded by non-malignant prostatic inflammation.

Matrix metalloproteinases (MMPs) are emerging as promising diagnostic and prognostic biomarkers for prostate cancer (PCa). This study explored the association between urinary exosome MMP levels and the incidence of prostate cancer. Urine samples were collected from patients undergoing prostate biopsy or prostatectomy, and from age-matched healthy controls. A total of 147 patients participated, including 37 patients who provided samples before prostatectomy, 41 patients before a biopsy that turned out positive, 21 patients before a biopsy that turned out negative, and 48 healthy controls. The study found that MMP-2 expression was similar in patients with prostate cancer and healthy controls but significantly higher in those with a negative biopsy. MMP-9 expression was elevated in patients with a positive biopsy and even higher in those with a negative biopsy. Multivariate logistic regression, adjusted for age, showed that increased MMP-2 expression was linked to a higher likelihood of a negative biopsy result (OR 1.12 [1.002,1.252], P = 0.046), while increased MMP-9 expression was associated with a higher probability of prostate cancer diagnosis (OR 1.106 [1.002,1.22], P = 0.045). These findings suggest that urinary MMP-9 levels are elevated in PCa patients, though even higher levels in biopsy-negative cases may reflect confounding factors such as benign prostatic inflammation.